1. Field of the Invention
The present invention relates to a circuit board laminate and a metal-based circuit board produced from the circuit board laminate.
2. Description of the Related Art
Electronics technologies have been remarkably developed in recent years and the developments of high-performance and miniaturized electrical and electronic equipment have made rapid progress. Along with this, the amount of heat generated by parts mounted with electrical elements and/or electronic elements are more increased. Such a background brings about a situation where excellent heat radiation ability besides sufficient thermal resistance is required for the metal-based circuit board that is typically equipped with so-called power devices such as MOSFETs (metal-oxide-semiconductor field-effect transistors) and IGBTs (insulated-gate bipolar transistors).
The metal-based circuit board has a structure in which an insulation layer and a circuit pattern are laminated in this order on a metal substrate. When this insulation layer is made of a mixture of a resin and an inorganic filler, a metal-based circuit board superior in heat radiation is obtained. Jpn. Pat. Appln. KOKAI Publication No. 5-167212 describes that alumina, silica, aluminum nitride, boron nitride, beryllium oxide, or a mixture of these compounds is used as an inorganic filler and an epoxy resin, phenol resin, silicon resin, or polyimide resin is used as a resin.
Jpn. Pat. Appln. KOKAI Publication No. 2005-325231 describes a resin composition obtained by filling a high heat-conductive inorganic material in a liquid crystal polyester having a specific structure. This literature describes that a mixture of two or more of materials selected from aluminum nitride, boron nitride, aluminum oxide, and the like may be used as the heat-conductive inorganic material. This literature also describes that this resin composition can be used as encapsulants for semiconductors, resistors, capacitors, etc., raw materials for electrical and electronic parts such as substrates and housings, or construction materials for equipment such as heat exchangers and bearings.